Ctrl-S Save failing when post date is in the future?

Ok, a bit confusing but I’m curious if this is just me, or if it’s a bug.

I have some posts in draft status. I edited the Post dates to be in the next day or so, then continued to work on them. I save pretty religiously using Ctrl-S, and did so repeatedly. I saw the usual confirmation at the bottom of the post window – “Saving Draft…” then “Draft saved at <time>”. So far so good.

Then I left the page, did something else, and came back. Most of my post was missing. It turns out that everything it claimed to have saved via Ctrl-S was lost.

Testing has shown that if I click on the “Save Draft” button, changes are successfully saved, but if I use Ctrl-S, they are lost – despite the message saying the draft was saved. In Revisions, I only have drafts saved via the button, never via Ctrl-S.

I have never had this trouble before, and if I remove the future date, Ctrl-S saves fine again. It sounds awfully like this is to do with having a future date for the post.

Any thoughts? Thanks!